1. Field of the Invention
The present invention relates to fluid viscometers for measuring the viscosity of fluid in a conduit such as pipe or manifold, and more particularly, to turbine viscometers that can provide a viscosity measurement of flowing fluid without the necessity of any mechanical penetration through the pipe or manifold.
2. Description of the Prior Art
The measurement of the viscosity of a fluid flowing in a pipe or other conduit is well known but can be problematic. Particularly difficult fluids to measure are fracturing fluids and gels used in fracturing of well formations. The viscosity of the fluid is, of course, measurable before it is pumped into the well, but this measurement is not always satisfactory because the viscosity of the fluid may change in the well. Heat and other well conditions may affect the fluid in ways that are not entirely predictable.
Therefore, it is desirable to be able to measure the viscosity of such fluids “on the fly” as the fluid is flowing through the pipe. Currently, there is no known in-line device which can be used for measuring full stream on most fracturing treatments. Current technology requires that the fluid be free of proppants, so any measurements taken are not accurate.
The present invention solves this problem by providing a turbine rotatable in the pipe such that the rotation of the turbine can be determined magnetically. The magnetic slip or drag on the turbine is a function of fluid shear in the fluid being measured, and this is proportional to viscosity. The turbine can be rotated by a rotating magnetic field external of the pipe or by a drive turbine which is rotated by the fluid flow. Electromagnets and pickups can be embedded in the wall of the pipe with no mechanical penetration therein.